Packard, Stanford researchers uncover gene family critical to asthma development

November 29, 2001

STANFORD, Calif., Nov. 29, 2001 - A novel gene family that appears critical to the development of asthma in mice has been identified by researchers at Lucile Packard Children's Hospital at Stanford. The finding may revolutionize treatment and diagnosis of the more than 15 million people in the United States who suffer from asthma. It may also explain why incidence rates have climbed rapidly in industrialized countries over the past 20 years, say the researchers.

Asthma researchers have known for years that the disease has a genetic component, but efforts to pinpoint specific genes have been stymied by the complexity of the disease, which involves more than a dozen independently acting genes. When the Stanford researchers used a special technique to look at the effects of only small stretches of DNA at a time, however, they identified a previously unknown group of nearby genes, called the Tim family, as primary culprits.

"It was only by using this mouse model that we could identify a locus and some potential candidate genes that could be inducing this phenomenon," said Rosemarie DeKruyff, PhD, senior author of the study, published in the December issue of Nature Immunology. "It was especially interesting when we found that the gene we homed in on encoded the hepatitis A receptor gene."

Infection with hepatitis A protects against asthma for reasons that have not been well understood. The newly discovered link between family member TIM-1 and the hepatitis A virus may help explain the association between the two diseases. Researchers speculate that binding of the virus to the hepatitis A receptor gene, TIM-1 somehow interferes with disease development in these infected individuals. If so, their finding may provide a clue as to why asthma rates have increased where hepatitis A infection rates have dropped over the past two decades.

"It may be that when hepatitis A binds to this receptor it somehow brings about a deletion of those cells that bias the immune response toward asthma," says DeKruyff, a professor of pediatrics at Packard. "But there are also other possible scenarios."

To carry out the research, Jennifer McIntire, an MD/PhD student working in DeKruyff's lab in collaboration with Dale Umetsu, MD, PhD, chief of the division of allergy and immunology, bred together two sets of mice. One set develops airway hyperreactivity, or AHR, after being exposed to an allergen, and another is resistant to AHR, which causes the shortness of breath, chest tightening, wheezing and coughing that are hallmarks of human asthma attacks.

Using a technique known as backcrossing, McIntire and her colleagues generated mice that were genetically identical to the susceptible mice, other than for small segments of DNA from the resistant group. They then looked for mice in the group that did not develop AHR when exposed to an allergen.

They found that mice containing a small segment of DNA similar to an asthma susceptibility region on human chromosome 5 were significantly less likely to develop AHR than the susceptible group, even though the two groups shared the rest of their genomes.

The region on human chromosome 5 contained some likely candidate genes, including several encoding proteins called cytokines that regulate the immune response leading to asthma. Many researchers had assumed that these cytokine genes were responsible for the increased asthma susceptibility conferred by the region. However, when McIntire and her colleagues analyzed the stretch of DNA more closely they found that the development of AHR was actually linked to a nearby group of genes, which they named the Tim family.

The researchers are now investigating whether this gene family is also linked to the development of asthma in humans.
DeKruyff's and McIntire's Stanford colleagues on the study include undergraduate Sarah Umetsu; Omid Akbari, PhD; and Dale Umetsu, MD, PhD, all in the division of allergy and immunology in the Department of Pediatrics; and Gregory Barsh, MD, PhD, in the Howard Hughes Institute and Departments of Pediatrics and Genetics.

Lucile Salter Packard Children's Hospital at Stanford is a 240-bed hospital devoted entirely to the care of children and expectant mothers that is celebrating its tenth anniversary in 2001. Providing pediatric medical and surgical services associated with Stanford University Medical Center, Packard offers patients locally, regionally and nationally with the full range of health care programs and services - from preventive and routine care to the diagnosis and treatment of serious illness and injury. To learn more about Lucile Packard Children's Hospital, please visit our Web site at

Contact: Matt Lash
Phone: (650) 497-8364
Pager: (415) 607-2629

Stanford University Medical Center

Related Asthma Articles from Brightsurf:

Breastfeeding and risks of allergies and asthma
In an Acta Paediatrica study, exclusive breastfeeding for the first 3 months was linked with a lower risk of respiratory allergies and asthma when children reached 6 years of age.

Researchers make asthma breakthrough
Researchers from Trinity College Dublin have made a breakthrough that may eventually lead to improved therapeutic options for people living with asthma.

Physics vs. asthma
A research team from the MIPT Center for Molecular Mechanisms of Aging and Age-Related Diseases has collaborated with colleagues from the U.S., Canada, France, and Germany to determine the spatial structure of the CysLT1 receptor.

New knowledge on the development of asthma
Researchers at Karolinska Institutet in Sweden have studied which genes are expressed in overactive immune cells in mice with asthma-like inflammation of the airways.

Eating fish may help prevent asthma
A scientist from James Cook University in Australia says an innovative study has revealed new evidence that eating fish can help prevent asthma.

Academic performance of urban children with asthma worse than peers without asthma
A new study published in Annals of Allergy, Asthma and Immunology shows urban children with poorly controlled asthma, particularly those who are ethnic minorities, also suffer academically.

Asthma Controller Step Down Yardstick -- treatment guidance for when asthma improves
The focus for asthma treatment is often stepping up treatment, but clinicians need to know how to step down therapy when symptoms improve.

Asthma management tools improve asthma control and reduce hospital visits
A set of comprehensive asthma management tools helps decrease asthma-related visits to the emergency department, urgent care or hospital and improves patients' asthma control.

Asthma linked to infertility but not among women taking regular asthma preventers
Women with asthma who only use short-acting asthma relievers take longer to become pregnant than other women, according to research published in the European Respiratory Journal.

What are the best ways to diagnose and manage asthma?
A team of experts from The University of Texas Medical Branch at Galveston examined the current information available from many different sources on diagnosing and managing mild to moderate asthma in adults and summarized them.

Read More: Asthma News and Asthma Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to